1. Field
A compressor is disclosed herein.
2. Background
In general, a compressor is applicable to a vapor compression type refrigeration cycle (hereinafter, abbreviated as a “refrigeration cycle”), such as a refrigerator, or air conditioner. For a refrigerant compressor, there has been introduced a constant speed compressor, which is driven at a predetermined speed, or an inverter type compressor, in which a rotation speed is controlled.
A compressor can be divided into a hermetic type compressor, in which an electric motor drive, which is a typical electric motor, and a compression unit or device operated by the electric drive are provided together at an inner space of a sealed casing, and an open type compressor in which an electric motor is separately provided outside of the casing. The hermetic compressor is mostly used for household or commercial refrigeration equipment.
The hermetic compressor may be divided into a single hermetic compressor and a multiple hermetic compressor according to a number of cylinders. The single hermetic compressor is provided with one cylinder having one compression space within the casing, whereas the multiple hermetic compressor is provided with a plurality of cylinders each having a compression space, respectively, within the casing.
The multiple hermetic compressor may be divided into a 1-suction, 2-discharge type and a 1-suction, 1-discharge type according to the refrigerant compression mode. The 1-suction, 1-discharge type is a compressor in which an accumulator is connected to a first cylinder among a plurality of cylinders through a first suction passage, and a second cylinder is connected to a discharge side of the first cylinder connected to the accumulator through a second suction passage, and thus, refrigerant is compressed by two stages and then discharged to an inner space of the casing. In contrast, the 1-suction, 2-discharge type is a compressor in which a plurality of cylinders are branched and connected to one suction pipe and refrigerant is compressed in the plurality of cylinders, respectively, and discharged to an inner space of the casing.
FIG. 1 is a longitudinal cross-sectional view of a related art 1-suction, 2-discharge type rotary compressor. As illustrated in the related art 1-suction, 2-discharge type rotary compressor, a motor drive 2 is provided within the casing 1, and a compressor unit or device 3 is provided at a lower side of the motor drive 2. The motor drive 2 and compressor unit 3 are mechanically connected through a crank shaft 23. Reference numerals 21 and 22 denote a stator and a rotor, respectively.
For the compressor unit 3, a main bearing 31 and a sub bearing 32 are fixed to the casing 1 at regular intervals to support the crank shaft 23, and a first cylinder 34 and a second cylinder 35 separated by an intermediate plate 33 are provided between the main bearing 31 and sub bearing 32. An inlet port 33a connected to a suction pipe 11 is formed at or in the intermediate plate 33, and a first suction groove 33b and a second suction groove 33c that communicate with each compression space (V1, V2) of the first cylinder 34 and second cylinder 35 are formed at an end of the inlet port 33a. 
A first eccentric portion 23a and a second eccentric portion 23b are formed on the crank shaft 23 along an axial direction with a distance of about 180° therebetween, and a first rolling piston 36 and a second rolling piston 37 to compress refrigerant are coupled to an outer circumferential surface of the first eccentric portion 23a and the second eccentric portion 23b, respectively. A first vane (not shown) and a second vane (not shown) welded to the first rolling piston 36 and the second rolling piston 37, respectively, to divide first compression space (V1) and second compression space (V2) into a suction chamber and a compression chamber, respectively, are coupled to the first cylinder 34 and the second cylinder 35. Reference numerals 5, 12, 31a and 32a denote an accumulator, a discharge pipe, and discharge ports, respectively.
According to the foregoing related art 1-suction, 2-discharge type rotary compressor, when power is applied to the motor drive 2 to rotate the rotor 22 and the crank shaft 23 of the motor drive 2, refrigerant is alternately inhaled into the first cylinder 34 and the second cylinder 35 while the first rolling piston 36 and the second rolling piston 37 revolve. The refrigerant is subjected to a series of processes of being discharged into an inner space of the casing 1 through the discharge ports 31a, 32a provided in the main bearing 31 and the sub bearing 32, respectively, while being compressed by the first vane of the first rolling piston 36 and the second vane of the second rolling piston 37.
However, according to the foregoing 1-suction, 2-discharge type rotary compressor, the first eccentric portion 23a and the second eccentric portion 23b are eccentrically formed at regular intervals with respect to an axial center in a lengthwise direction of the crank shaft 23, and thus, a moment due to an eccentric load is increased, thereby causing a problem of increasing vibration and friction loss of the compressor. Further, each vane is welded to each rolling piston 36, 37 to divide the suction chamber and the compression chamber, but according to operating conditions, refrigerant leakage is generated between each vane and each rolling piston 36, 37 while they are separated from each other, thereby reducing compressor efficiency.
Taking this into consideration, a 1-cylinder, 2-compression chamber type rotary compressor having two compression spaces in one cylinder has been introduced as disclosed in Korean Patent Registration No. 10-0812934. FIG. 2 is a longitudinal cross-sectional view of a related art 1-cylinder, 2-compression chamber type rotary compressor, and FIG. 3 is a transverse cross-sectional view of a cylinder and a piston in the 1-cylinder, 2-compression chamber type compressor of FIG. 2, taken along line “III-III” of FIG. 2.
As illustrated in FIG. 2, for a 1-cylinder, 2-compression chamber type rotary compressor (hereinafter, abbreviated as a “1-cylinder, 2-compression chamber compressor”) according to the related art, a first compression space (V1) and a second compression space (V2) are formed at an outer side and an inner side of the piston 44, respectively. Further, the piston 44 is fixedly coupled to an upper housing 41 and casing 1, and the cylinder 43 is coupled in a sliding manner, between the upper housing 41 and lower housing 42, to eccentric portion 23c of crank shaft 23 so as to be revolved with respect to the piston 44.
A long hole-shaped inlet port 41a is formed at one side of the upper housing 41 to communicate with each suction chamber of the first compression space (V1) and the second compression space (V2), and a first discharge port 41b and a second discharge port 41c are formed at the other side of the upper housing 41 to communicate with each compression chamber of the first compression space (V1) and the second compression chamber V2 and the discharge space (S2).
As illustrated in FIG. 3, the cylinder 43 may include an outer cylinder portion 45 that forms the first compression space (V1), an inner cylinder portion 46 that forms the second compression space (V2), and a vane portion 47 that connects the outer cylinder portion 45 and the inner cylinder portion 46 to divide the suction chamber and the compression chamber. The outer cylinder portion 45 and the inner cylinder portion 46 are formed in a ring shape, and the vane portion 47 is formed in a vertically raised flat plate shape.
An inner diameter of the outer cylinder portion 45 is formed to be greater than an outer diameter of the piston 44, and an outer diameter of the inner cylinder portion 46 is formed to be less than an inner diameter of the piston 44, and thus, an inner circumferential surface of the outer cylinder portion 45 is brought into contact with an outer circumferential surface of the piston 44 at one point, and an outer circumferential surface of the inner cylinder portion 46 is brought into contact with an inner circumferential surface of the piston 44 at one point, thereby forming the first compression space (V1) and the second compression space (V2), respectively.
The piston 44 is formed in a ring shape, and a bush groove 49 is formed to allow the vane portion 47 of the cylinder 43 to be inserted thereinto in a sliding manner, and a rolling bush 48 is provided at or in the bush groove 45 to allow the piston 44 to make a turning movement. The rolling bush 48 is disposed such that flat surfaces of a semicircular suction side bush 48a and a discharge side bush 48b are brought into contact with the vane portion 47 at both sides thereof.
On the drawing, unexplained reference numerals 43a and 44a are lateral inlet ports.
According to the foregoing related art 1-cylinder, 2-compression chamber compressor, the cylinder 43 coupled to the crank shaft 23 makes a turning movement with respect to the piston 44 to alternately inhale refrigerant into the first compression space (V1) and the second compression space (V2), and the inhaled refrigerant is compressed by the outer cylinder portion 45, the inner cylinder portion 46, and the vane portion 47, and thus, alternately discharged into an inner space of the casing 1 through the first discharge port 41b and the second discharge port 41c. 
As a result, the first compression space (V1) and the second compression space (V2) may be disposed adjacent to each other on the same plane, thereby reducing moment and friction loss. In addition, the vane portion 47, which divides the suction chamber and compression chamber, may be integrally coupled to the outer cylinder portion 45 and the inner cylinder portion 46, thereby enhancing sealability of the compression space.
However, according to the foregoing related art 1-cylinder, 2-compression chamber compressor, the piston 44 is fixed, but the relatively heavy cylinder 43 is rotated, and thus, a high power loss results with respect to the same cooling power and a large bearing area, thereby increasing concerns of refrigerant leakage.
Further, according to the related art 1-cylinder, 2-compression chamber compressor, part of an outer circumferential surface of the cylinder 43 may be closely adhered to an inner circumferential surface of the upper housing 41, and thus, a diameter of the upper housing 41 should be increased to change a volume of the cylinder 43 according to turning movement, and consequently, the casing 1 itself should be changed in an increasing manner, thereby causing a problem in which volume control of the compressor is not so easy.
Furthermore, according to the related art 1-cylinder, 2-compression chamber compressor, the first discharge port 41b and the second discharge port 41c may be formed to extend in the same direction, and thus, refrigerant being discharged first may lead to a so-called pulsation phenomenon, thereby aggravating vibration noise of the compressor.